1. Field of the Invention
This invention relates to apparatus for use in leak testing of pipe joints by means of a pressurized test gas, and more particularly to an enclosure device for confining liquid around a pipe joint to permit the visual detection of test gas that leaks through the joint.
2. Description of the Prior Art
The testing of fluid conduits for leak tightness is a common requirement, especially in the oil and gas well field. In the oil field, the testing of pipe joints is especially important to prevent leakage of the gas or oil out of the pipe and loss into the surrounding ground around the bore hole. Typically in such applications, a hole is drilled in the earth, and as the depth of the hole increases, a well casing, in the form of a pipe, is inserted behind the drill to define the wall bore and to permit the introduction and withdrawal of drilling fluids, as well as the withdrawal of drilling debris. Several sections of such a well casing are referred to as a well string, and the string is defined by a series of interconnected pipe sections, the interconnections most often being accomplished by means of an internally threaded union which engages corresponding external threads at each of the opposed ends of the pipe sections to be joined.
Testing of such pipe joints for leak tightness has most often been accomplished by subjecting the pipe joint to high internal fluid pressures. A suitable pipe testing tool is introduced into the interior of the pipe, the tool being such that it includes spaced resilient packing glands which are radially outwardly expandable against the interior surface of the pipe on opposite sides of the area to be tested to thereby define a confined annular space into which a pressurized liquid, such as water, can be introduced. Any leakage of water through the joint can then be visually detected, whereupon suitable corrective action can be taken.
In addition to the use of pressurized water, it has become the preferred practice when testing pipe for the deeper wells to employ pressurized gases, specifically nitrogen gas, to check pipe joints for leak tightness because the gases are capable of passing through, and thereby exposing, smaller leak sites than is water. This is particularly true for testing leak tightness at pressures in excess of about 10,000 psi. When pressurized nitrogen or another test gas is used, a cup-like member is positioned around and under the exterior of the joint section to be tested, which tightly engages the section of pipe immediately below the test section to define an external annular chamber open at the top and closed at the bottom. Water is placed in the annular chamber, and a leak manifests itself by the appearance of gas bubbles rising in the surrounding water, which can be visually detected. An example of such a "bubble bucket" is shown in U.S. Pat. No. 3,385,103, issued May 28, 1968, to John F. Wilkerson. However, the Wilkerson device is a cylinder that has a continuous sidewall and openings at each end. Therefore that device cannot be removed from a pipe in a lateral direction, but must be moved axially along the pipe until the end of the pipe is reached, and thus removal of the Wilkerson device from a pipe string is cumbersome and inconvenient. Also, the Wilkerson device requires the use of a flexible sealing disk, formed of rubber or other flexible material, to allow relative movement between the disk and the pipe while maintaining a seal and to permit passage of a pipe joint therethrough.
It is desirable that an improved leak test enclosure be provided which is more convenient to use and which can be rapidly applied to or removed from the pipe connection to be tested. It is also desirable that an improved leak test enclosure be provided which does not require specially designed sliding seals and the like.